Keep the Laptop or go for the Tablet?

Nomad

mash2 - Boy, couldn't tell ya as I've never had/used a PSB. Pixelmator is my go to for my night shots as all I'm doing is image (layer) stacking. Take a look at Affinity Photo. It's a more heavy duty PS replacement so it might.
By the way - not sure I mentioned this before - you've got some really nice shots. Can't imagine working with 25,000 pixels - what's the file size like. Mine run in the 1-3 gig range depending on the number of exposures (layers)

mash2

I'm combining up to 100 - 36mg files to get the size I want (my standard print size is 1 1/2 foot by 5 foot or 2 1/2 foot by 5 foot).  I have my own 44 inch printer.  My file size runs from 1.5 gb to 6 gb.  I'm pretty consistently over the PSD file size limit for programs, so I use PSB format to move between software.  

I'll check out Affinity, it reads PSB files.  I'm actually running my stuff thru 6 separate programs at this point in time.  I use photoshop as an orchestrator more than anything.  My process is to develop raw, correct lens distortion, HDR for separate images, pano program for combining images and then minor clean up in photoshop and Viveza (a google program that is really powerful and intuitive).   

I keep ramping up print sizes so I need higher resolution.  As long as I can continue to exhibit and sell some, I'll keep working at getting massive detail.